Signaling system



April 2, 1940 c. J. FITCH SIGNALING SYSTEM Original Fired Dgc. 7, 1934, s Sheets-Sheet 1 ATTORNE April 2, 1940.

c. J. FITCH SIGNALING syswmi 3 Sheets-Sheet 2 Original Filed Dec. 7, 1934 7 FIG. 3. I

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PAWS! 7 z e m M P w ATTORNEY 3 Sheets-Sheet 3 C. J. FITCH SIGNALING SYSTEM Original Filed bec 7, 1934 April 2, 19 40.

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M4 ATTORNEY Patented Apr. 2,1940

UNITED STATES PATENT OFFICE SIGNALING SYSTEM Clyde J. Fitch, Endicott, N. Y., assignorto International Business Machines Corporation, New York, N. Y., a corporation of New York 4 Claims.

This invention relates to signaling systems and more particularly to an electronic signal receiving system, and is a'division of the co-pending application Serial No. 756,443, filed December 7,

1934, now Patent No. 2,153,178, dated April 4, 1939.

An object of the present invention is the provision of a method of and means for controlling selectively and independently the operation of a plurality of electric discharge devices operating in synchronism with the incoming signal impulses.

Another object of the present invention is to provide a plurality of circuits including static control means which are conditioned periodically in a definite sequence in accordance with predetermined conditions of a varying voltage supply to. receive incoming timed impulses, either singly or in combination.

Another object is the provision of independent operation of each of the said plurality of circuits.

Another object is the provision whereby the control element operation is controlled in a predetermined manner upon reception of a single signal impulse of a series of impulses, or controlled only upon the reception of a predetermined number of impulses in said series.

Further objects of the instant invention reside in any novel feature of construction or operation or novel combination of parts present in the embodiment of the invention describedand shown in the accompanying drawings whether within or without the scope of the appended'claims and irrespective of other specific statements as to the scope of the invention contained herein.

In the drawings:

Fig. l is a sectional view of one type of standard translating mechanism. 7

Fig. 2 is an exploded view of certain control elements of the translating mechanism; the structural features of which are exaggerated to show clearly the normal operating positions thereof.

Fig. 3 shows a detailed arrangement of the permutation bar'unitin a receiving translating unit.

45 Fig. 4 shows a detailed permutation bar arrangement in a transmitting translating unit.

Fig. 5 shows diagrammatically and vectorially one arrangement of the transformer'windings as embodied in the present invention.

50 Fig. 6 shows the circuit connections of an individual electric discharge device as embodied in the present invention.

Figs. 7 to 9 show graphically the wave shape forms impressed on various sections of the cir- 55 cuits shown.

Fig. 10 shows graphically the developed phase displaced impulses initiated by the impulse generator arrangement.

Fig. 11 shows graphically a combination of impulses representing a desired characterization. 5

Fig. 12 shows diagrammatically a preferred form of the signal, impulse generator and receiver circuit arrangement.

The said co-pending application shows how the present invention may be usedin one type of 10 printing telegraph system as a signal impulse generator and receiver; however, it is to be understood that the application of the present invention is not limited to printing telegraph systems but is applicable to any system utilizing 15 timed control impulses either singly or in combination therewith.

A description will now be given of one method of controlling the operation of the control contacts of the signal impulse generator and how 20 the incoming signals may be utilized to operate a specific unit applicable to printing telegraph systems.

For illustrative purposes, this invention is shown as embodying a well known type of re- 25 cording unit, which may be similar in construction to the Electromatic typewriter, shown and described in detail in U. S. Patent No. 1,777,055, and hence requires only the following brief description. 30

Referring to the drawings and particularly to Fig. 1, well known means are provided for actuating the type bars l6, comprising a constantly rotating roller 10, cooperating with a series of individual power units each comprising a cam H, the engagement of the cams with the roller being controlled selectively by the character key I bars H.

Any suitable means may be provided to rotate the power roller, in the direction indicated by the arrow, which is adapted'to cooperate with two rows of cam units arranged in the front and rear of the roller. The cam H may be provided to be pivoted on one arm of a bell crank lever 82 which is pivoted in the frame of the recording unit, as indicated generally by reference character l 3, the other arm of the said bell crank lever is operatively connected with an arm of bell crank lever l4 by means of link l5. Another arm of the said lever I4 is connected to the type bars iii in a well known manner, so as to efiect operation of the type bars or any other suitable means connected to the bell crank levers upon selective 1 operation of the controlling key bars I1.

I'he pivoted bell crank lever I2 isoperated by the associated cam ll whenever the latter engages the driven roller; the engagement of the cam withthe roller is controlled .by means of the associated control key bar IT in a manner which will now be briefly described.

Referring now to Fig. 2, the cams occupy normally the positions as shown in this figure, which represents one of the rear bank of the units. In this position the impeller-arm I8 is urged, by the associated coil spring l9, against one of the impeller-lugs 20, which at the time is in the lower position, and tends to turn the cam II in a clockwise direction. This is prevented, however, by the engagement of one of the detents 2| on the cam, with the upper stop lug 22 on the stop lever 23. If, howevenjthe corresponding key bar is operated, the bifurcated lower end (Fig. 1) of extension arm 24 associated with one of the said key bars I! engages an arm 25 at the upper end of the stop lever 23 which is provided with an offset projection at its end which extends laterally through an opening in the bell crank lever l2. The arm 25 of the stop lever 23 is then swung rearwardly or to the left as viewed in Fig. 1 about the pivot 26 and its lower end forwardly or to the right as viewed in this figure, thus releasing the cam, which then turns under the influence of the spring urged impeller-arm l8. In doing so the upper serrated lobe of the cam is brought into engagement with the power roller, which turns in a counterclockwise direction and therefore causes a continued rolling movement of the cam until the high point has been reached and passed. This causes the whole cam unit to swing around the pivot l3 so as to pull down the corresponding link and actuate one of the type bars or any other mechanism with which the cam unit may be connected.

After the high point of the cam is passed, the cam loses contact with the roller but the said impeller-arm I8 tends to continue the rotation thereof by engaging the second impeller-lug 29 of cam H until the second detent 21 engages one of the stop lugs. Since the half rotation of the cam consumes 0n.y a small fraction of a second, it is diflicult to release the key bar within this short interval, so that it is the lower lug 28 which is st engaged, butupon the release of the key bar nd the return of the stop lever 23 to normal position, this lug 28 disengages the detent, whereupon the impeller-arm rotates the cam slightly and the said detent then engages the upper stop lug 22.

It is obvious then that depression of a key bar releases the revolubly mounted cam to engage and be actuated by the power roller in turn operating the associated bell crank lever and its attached links to cause theassociated mechanism such as the-type bars and other operating mechanism to be operated. It is to be understood that an individual cam unit is provided for each type bar or other functional mechanisms associated therewith.

The action of the cam mechanism has been described with respect to one of the rear banks of cam units; in the case of those of the forward banks the operation is analogous, but the directions of movement and the order of operation of the stop lugs are. reversed. For example, if the bifurcated arm 24-a is positioned to engage the arm 25-a at the upper end of the stop lever 23-a by virtue of operation of the associated key bar, the said arm is positioned rearwardly or to the left as viewed in Fig. 1. and

the lower end of the stop lever 23--a is moved forwardly, that is, to the right as viewed in the said figure. This said operation is effective to release the cam, by virtue of positioning the lower stop lug 28-a out of the path of detent 2|a, thus permitting the spring-urged impeller arm lB-a to rotate the cam slightly in a clockwise direction to effect engagement of the lower lobe of cam II and power roller. Upon completion of a half revolution of the cam II, the second detent 2'l-a engages first the upper stop lug 22-a while the stop lever 23--a .is in an operated position, but upon release of the associated key bar and the return of the said stop lever to normal position, this lug 22a disengages the said detent and the impeller-arm rotates the cam slightly so that the said detent then engages the lower stop lug 28a, as shown in the figure. In this manner the bell crank lever i2-a is rotated about the pivot I3-a to operate the associated type bar or any other mechanism associated therewith. For further structural details of the cam units, reference should be made to the above mentioned patent.

When it is desired to employ the unit just described as a transmitting device to control the initiation of the timed control signals corresponding to the selected characters, a permutation oar unit may be associated with the key bars I! to operate seiectively the associated control contacts. Application of permutation bars in printing telegraphy is well known; therefore, a detail view of a permutation bar unit as shown in Fig. 4 is deemed sufficient. In the said figure a group of eight permutation bars 29-a are shown disposed beneath the key bars IT. The present illustration is based on employing a code using a combination of three out of the total eight for each character representation. It is obvious that any desired combination may be used. In the figure, the key 'bar shown upon operation is effective to operate the I, 2 and 6 permutation bars which in turn are effective to operate the associated individual contacts 30 for purposes understood as the description progresses.

When the translating unit is employed as a controlled device similar permutation bars 42 (Fig. 3) may be associated with the key bars I1 and connected individually to links 43 associated with armatures 44 controlled by individual magnets 45. Energization of any selected groups of the magnets is effective to operate the corresponding permutation bars 42 to select a single control key bar ll, in the well known manner; for example, as shown in Fig. 3 energization of the magnets associated with the I, 2 and 6 permutation bars 42 is effective to select and render operative the particular character key bar I! shown in the figure.

Other methods of controlling translation units may be employed; for example, reference may be made to U. S. Patent 1,996,013 wherein a method of controlling the control contacts and operation of the key bars is shown'employing single control means to effect operation of the transmitting circuits and to control the operation of the key bars instead'of the comblnational code means just described.

The electronic signal generating and receiving circuits will now be described. Referring now to Fig. 6, a single signal generating circuit will be described first, and in the disclosed form is shown to comprise an electric dischargedevice T comprising the combination of a full wave rectifier and trlode in one envelope and is a type known in (ill contacts 30 which are included in a circuit comthe art as a duplex diode triode type, The diode plates 3| and 32 are joined to the terminals of resistance Rrl which is connected in shunt relationship with the secondary winding 33 of transformer 34. The center tap. of the said resistance is connected to the control grid element 35 of the tube and is also connected to a second resistance R inserted between the said center tap The triode plate is and the cathode element 36. connectedto a set of control elements such as prising the primary winding of transformer 38, battery 39 and connected to the said cathode element. 1

It is evident from the description of the circuit' connections just set forth that normally the grid element of the tube. is at zero bias, due to the fact that. no current is passing through the resistor R; therefore, upon closure of contacts 30 current flow will be established in the triode plate circuitas follows: from the positive terminal of battery 39 through the primary winding of'transformer 38, contacts 30, anode and cathode elements of the tube to the negative terminal of the said battery. However, the condition just described exists in the said circuit for only av com paratively short time, because the bias on the grid 35 is not a constant factor but varies in timed relationship with the frequency of the connected A, C. supply source.

respect to the cathode which is of sufficient value to prevent further flow of plate current. in the stantially zero value, a pulse is impressed upon the output circuit of the triode in which the transformer 38 is included. If the contacts 30 are maintained in an operated condition for a number of complete cycles of the supply source, a control pulse is initiated automatically each time the voltage condition of the rectified supply passes through zero, thus initiating a series of equally spaced and timed control pulses. By 1 e' ferring to the graphic representations in Figs. '1 to. 9, the voltage conditions in the various sections of the-circuit are shown; Fig. 7 shows the alternating voltage supply wave forms impressed on the diode plates; Fig. 8 shows the rectified voltage wave forms impressed on the resistance R and Fig. 9 shows the series of short equally spaced and accurately timed pulses or control signals impressed on the triode output circuit.

The circuit just described has shown one methodof converting a single phase sinusoidal wave By referring now to Fig. 12, it will be underw stood how the out-of-phase impulses are generated. The individual circuits embodying the individual electric discharge devices T-l to. T--8' are separately connected to different output terminals of a phase-splitter or transformer 40, so that a voltage supply of different phases is impressed oneach of the diode plates of the tubes T--l to T-8. By referring to Fig. 5, it is shown diagrammatically and vectorially how two transformers A and B, each having a plurality of secondary windings, the number of which is depend-. entupon the number of phases to be generated,

The said supply is im-- 3 pressed on the full wave rectifier and, therefore, 'the rectified voltage impressed on resistance R immediately drives the grid bias negative with are connected for supply into a plurality of phases.

In the primary circuit of one transformer API is a condenser C to cause the current to lead the voltage, and in the primary of the other BP-2,is an inductance-L to cause the current to lag the voltage. The values of C and L are cho. sen so that the current flow in the primary windings are ninety degrees out of phase.

Primary winding AP--] is shown to have seven secondary windings AS-l and primary winding BP--2 has seven secondary. windings 33-! connected as shown. The turns ratio .of the individual secondary windings vary for each phase connection, and the turns ratio of the connected secondary windings of both transformers. are such that the voltage output for the 'open circuits are equal. The phase direction is shown vectorially by the arrowsfor each separate phase developed. This arrangement and connection of the priconverting the single phase maries and the secondaries of the said'transformers resultsin eight separate secondary cirthat, the impulses for each phase are displaced with respect to each other by twenty-two and a half electrical degrees. By referring to Fig. 10,

, signal impulse representations are shown for each of the phases. Since no two impulses overlap or occur at the same time, any number of; phases may be transmitted over-the selected type'of transmission system. For this reason the contacts 30 may be all connected simultaneously to a common circuit including the outputtransformer 38 as shown, which inturn is' then connected to asuitable amplifier and signal impulse transmitter 4| or for certain c'onditionsto the transmission medium directly;

It is obvious now that timed signal impulses may be transmitted upon closure of one, or more transmit character representations includin combinational groups of timed impulses, the contacts 30 may be operated simultaneously in any combination to initiate the combinational group of impulses; forexample, in Fig. 4 the contacts 30 associated withphases L2 and 6 and tubes T-l, T2 and T-B are operated by the charac-f.

ter key bar l1 shown upon operation of the key bar Fl to connect the said tubes to the common output circuit.

l of the control contacts 30. Where it is desired to In this manner, each tube circuit p aril y 1 becomes an independent impulse generator, the

] conditioning of each circuit being independent of the conditioning of the other. The impulses initiated' by each circuit when the tubes are rendered conductive are displaced in phase with respect to any other series of impulses generated by the remaining circuits. The length of time each circuit is maintained operative is also independent with respect to the remaining circuits,

that is, the individual contacts 30 may be controlled so as to be closed for a timed interval so that a single impulse is. generated or may be closed for a longer interval of time to initiate a series of equally spaced impulses as long as the contacts remain closed.

The signal receiving means comprises'in part a group of electric discharge devices RT I to RT8 similar to' the devices T-l to T! described hereinabove, and similar associated control circuits so as to control the operation or conductivity thereof similarly as described in respect with the devices T-l to T-8.

The diode plates of the said devices RT| to RT8 are connected separately to the individual and different phase outputs 1 to 8 of the phase transformer 40-a which is identical to the phase transformer 40 and described in detail hereinabove and, therefore, need not be repeated here. It should be mentioned at this time that the A. C.

supply sources impressed upon both the phase transformers 40 and 4lIa must be in synchrom'sm with each other; for purposes of description it can be assumed that the A. C. supply source is common to both transformers or that separately synchronized supply sources are impressed thereon. Similarly, as in transformer 40, the output circuits of transformer 40-41 supply individual voltages to the tubes RTI to RT! but each output thereof differing in phase with respect to each other by twenty-two and a half electrical degrees.

To simplify the description to follow, a single channel of the receivingcircuit,namely,thechannel associated with device RT--| will be described first and this description, of course, applies to the remaining channels of the signal impulse receiver. The diode plates of tube RT-l are connected to the secondary winding indicated phase I of the transformer ll-a and the shunt connected resistance AR-I. Thus, the said supply is impressed on the diode plates of tube RT-I in exactly the same time relationship as the supply impressed on diode plates of tube Tl. A resistance AB is connected from the cathode element to the center tap of resistance ARI, and the grid element of tube RTI is also connected to the said center tap, so that the rectified supply is impressed on the associated resistance AR to condition the grid element periodically to render the tube RT--I conductive similarly as described hereinabove with respect to tube T-l It is evident that the grid bias of tube RT--I varies similarly as the grid bias of tube T--l and in exactlythe same time relationship, that is, when the grid bias of tube RT- I is practically zero, this exact condition is present in tube T-l. Thus, it is seen that the grids of tubes T l and RT are conditioned in synchonism to render the said tubes conductive (when the grid bias approaches zero value), and that the bias on the said grids at all other times are of such value as to control the conductivity of the tubes, so as to suppress the flow of current in the associated output circuits. A condenser C-l and resistance CR-l are included in'the output circuit of the said electric discharge device RT-I, and are connected to the cathode element of the said tube and the anode element 50 ofthe tube ii. The grid element 52 of the last mentioned tube is connected to the secondary winding of transformer 53 and a source of supply to normally bias the tube 5| so that no current flows in its output circuit.

Now let it be assumed that the contacts 30 associated with tube T-I are operated to initiate a series of short equally spaced control signals which are received by any desired known type of receiving system 54 associated with the-secondary winding of transformer 53, or which may be impressed directly on the said transformer in certain cases. The received signals are effective to reduce the bias on the grid element 52 of tube II and render this tube conductive at the particular intervals the signals are received. During the said intervals the control signals are received, it is understood that the grid element of tube RT-I is so conditioned as to permit current to flow in the output circuit of this tube, for it was described how the tube RT--l is rendered conductive at the same intervals the tube T-I is conditioned to initiate the control signals, a circuit is now established momentarily from the negative potential supply associated with the cathode element of tube 5|, anode element of said tube, condenser and resistance CR I to cathode and anode elements of the tube RT-l to a positive potential supply associated with the said last mentioned anode element.

Energization of the described circuit charges condenser C-I and the resulting voltage drop across the resistance CR-l is effective to reduce the bias on the associated grid element of tube ATI permitting current to flow in its output circuit including the control element 45. The values of Cl and CR-I may be adjusted to control the operation of the tube AT--| in different ways, namely, the said elements may be of such values that the reception of the first signal of the series transmitted (or a single signal impulse) is effective to charge the condenser sufficiently and effect a voltage drop across the resistance to render the tube AT-'-l conductive immediately to activate the associated control element and be maihtained charged sufficiently by the following impulses to maintain the bias on the grid element of this said tube reduced sufficiently to allow a virtually steady current to flow in the output circuit of tube AT-l; or the values of the condenser and resistance may be adjusted, for example, that a predetermined number of signal impulses are necessary to be received to charge sufficiently the condenser C-I to render the tube AT-l conductive. It is evident that such changes in values of the control elements described to effect operation of the electric discharge devices in a predetermined manner and at predetermined timed intervals after reception of the signals, are encompassed in the scope of the present invention.

From the description just set forth, it will now be understood that, if signal impulses are received and impressed upon the tube at'intervals of time diflering from-the time intervals imparted to the signal impulses which as just described are effective to render the tube AT-l conductive, the tube ATI is not rendered con-' ductive by these first mentioned signals or, stated in other words, if the incoming signals impressed on the high biased tube 5| are not applied to the said tube in synchronism with the conductivity of tube RT-I, that is, at such timed intervals that tube RT-l is conditioned to permit current to flow in its output circuit, it is seen that the associated condenser C,-l will not be charged by said signals and consequently the tube ATI remains non-conductive. The reason for this is evident now, since it has been mentioned that only when the voltage applied to resistance AR passes through zero can the tube RTI pass current, and that all other times this tube remains blocked bythe grid bias applied thereto. However," the said second mentioned signals re-' ceived which are not in synchronisrn with the operation of tube RT-l or in phase therewith may be in phase with one of the other channelsembodying the tubes .RT2 to RT-8 to charge the corresponding condenser associated therewith impulses generated from the phase sources I, 2'

to render the corresponding tube AT-l conductive thereby energizing its output circuit.

electronic control distributors, is now understood,

and that the signals initiated by the tube circuit T-l associated with the phase I output of transformer 40 are effective only to render the tube AT-l conductive through the control tube R.Tl and that the signals initiated by tube T-2 are effective only to render conductive the tube AT-2 through the control tube RT-2, etc. Thus, it is seen that the different out-of-phase impulses are only effective to render the control circuits of the receiving system operative when the said signals are in phase with the conditioned control tubes RT-l to RT-O.

For example, let it be assumed that a character .key bar I! of the transmitting translating unit described is operated to displace the associated permutation bars 29-a numbers I, 2 and 6 (Fig. 4) thus operating the corresponding contacts 30 included in the output circuits associated with tubes T--l, T-2 and T-8 to initiate a corresponding series of out-of-phase impulses, namely,

and 6 (see Fig. 11).

' impulses are then' impressed upon tube 5| renassociated control device.

dering the said tube operative only at the intervals the signals are received. Since these signal impulses are in timed relationship with the conditioning of the tubes RTI,- RT-2 and RT6, current is permitted to flow in the associated output circuits to charge condensers C-l, -2 and 6-6, respectively thus conditioning tubes AT-i, AT-! and AT6 to permit current to flow in the respective output circuits energizing the control magnets 45 included in the said output circuits. Referring now to Figs. 1 and 3, energization of the said magnets 45 is effective to displace the permutation bars 42, numbers I, 2, and 6' to select the single key bar l1 corresponding to the signal combination, thus rendering the receiving translating unit operative to record the character corresponding to the character signal comprising impulses generated by phases I 2 and 8. It has now been shown how the control elements of two remotely situated series of electric discharge devices are conditioned or controlled in exact time relationship by certain voltage conditions of a synchronous alternating voltage supply to control the conductivity of the said devices when .the conditions of the said supply attain predetermined values soas to initiate automatically control signals, singly or in combinational groups, to render the second-series of devices effective to control the operation of an It has been shown that a single signal impulse of each phase is effective to render the associated controlled element operative, or that a series of predetermined timed signal impulses of each phase is necessary 'to render operative the said associated controlled element.

While there has been shown and described and pointed out the fundamental noyel features of the invention as applied to a single modification, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrative and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention therefore to be limited only as indicated by the scope of the following claims.

. What is claimed is:

1. A receiving system of the character described comprising means to receive variably timed signal impulses, a series of electric discharge devices, a sinusoidally varying voltage supply, means for impressing the said voltage supply upon the said devices including means for conditioning the devices sequentially and cyclically at exclusive intervals so that the devices can be rendered conductive at thesaid intervals, means controlled solely by the received signals for selectively rendering certain-of the devices conductive at the said intervals,-and means controlled by the said conductive devices.

2. A receiving system of the character described comprising normally inoperative electric discharge means rendered operative by the incoming variably timed signal impulses, a series of electric discharge devices, means including a sinusoidally varying voltage supply to condition the devices of the series sequentially and cyclically at exclusive intervals in synchronism with the signal impulses so that the devices can be rendered conductive at the said intervals, means controlled solely by the-first-mentioned means upon receipt of the signal impulses for selectively rendering certain of the devices conductive at the said intervals, and means controlled by the said conductive devices.

3. A receiving system 01 the character described comprising means to receive variably timed signal impulses, a multiphase sinusoidally varying voltage supply, means for rectifying the individual phases of said voltage supply, a series of electric discharge devices having grid and anode circuits, means for impressing the difierent phases of the rectified voltage upon corresponding devices of the series including individual means in the grid circuitsof said devices for conditioning the devices sequentially and cyclically at exclusive intervals as the rectified voltage supply passes through zero so that the devices can be rendered conductive at the said intervals, means controlled solely by the received signals for selectively rendering certain of the devices conductive at the said intervals, and-individual control means included in the said anode circults of the devices energized thereby whenever the devices are rendered conductive.

4. A receiving system of the character described comprising means to receive series of variably timed code signals, a series of electric discharge devices, means including a multiphase sinusoidal voltage supply to condition the devices of the series sequentially and cyclically at exclusive intervals so that the devices can be rendered conductive at the said intervals, and means controlled solely by the received signals for selectively rendering certain of the devices conductive at the said intervals including means for delaying the devices from being conductive until a predetermined number of the code signals of the series are received successively.

- CLYDE J. FITCH. 

